Multiresolution modeling and simulation of an air-ground combat application

The High Level Architecture (HLA) establishes a common modeling and simulation framework facilitating interoperability and reuse of simulation components. Since 1996, ONERA (French Aeronautics and Space Research Centre) carries out several studies on HLA in order to gain a better understanding of the underlying mechanisms of HLA implementations. The first critical step of this initiative was to develop our own RTI from the HLA specifications. In order to evaluate the cost of making a transition from legacy simulations to HLA, we first developed an HLA federation simulating an air-ground combat involving a set of aircraft's engaged against a surface to air defense system. Current studies on HLA distributed simulation include security, WAN simulations and multiresolution. Conventional simulations represent entities at just one single level of resolution. Multiresolution representation of entities consists in maintaining multiple and concurrent representations of entities. In this paper we address the problem of how HLA services may allow to achieve multiresolution modeling and simulation. Our goal is not to provide a general framework as a basis for designing simulations of entities at different levels of resolution concurrently. We focus on experience feedback we have obtained by migrating a single level resolution HLA federation to a multi-level resolution federation. The selected application is an air-ground combat simulation involving aggregated patrols of aircraft's engaged against a surface to air defense system. In this paper, we briefly describe the air-ground combat simulation application. We then detail the multiresolution representation of entities (patrols and aircraft's), and discuss the chosen mechanisms allowing triggering aggregation from an entity-level representation, and conversely, triggering disaggregation from an aggregate representation. We focus on the HLA services we have selected to maintain several levels of representation concurrently and on methodological issues in designing multiresolution HLA simulations. We have tackled some difficulties and we propose a new HLA service that should make easier the user's task. This multiresolution management service can be added to our RTI or written by using existing HLA services. Finally, future trends are discussed

Design and implementation of a HLA inter-federation bridge

In this paper, we discuss the design and implementation of a HLA inter-federation bridge. Our works are mainly motivated by the scalability and security problems, but we also consider the use of bridges for interoperability purposes. We describe several bridge topologies, including linear and cyclic inter-federations. We discuss problems raised by bridge federates and the use of different RTI implementations. We detail several solutions, leading to the design and implementation of a bridge prototype. Then we present our current results, and on-going works concerning performance improvements, interoperability, and security purposes

Une application pilote de simulation coopérative distribuée sous HLA (PRF SICODIS)

La modélisation et la simulation sont souvent employées par les chercheurs de l'ONERA, par les organismes de la Défense, par les industriels, pour concevoir et valider les systèmes complexes (systèmes de défense, systèmes d'information et de commandement, systèmes embarqués, etc.). Le Projet de Recherche Fédérateur (PRF)"SICODIS" s'intéresse en particulier aux simulations distribuées à événements discrets

PRISE: An Integrated Platform for Research and Teaching of Critical Embedded Systems

In this paper, we present PRISE, an integrated workbench for Research and Teaching of critical embedded systems at ISAE, the French Institute for Space and Aeronautics Engineering. PRISE is built around state-of-the-art technologies for the engineering of space and avionics systems used in Space and Avionics domain. It aims at demonstrating key aspects of critical, real-time, embedded systems used in the transport industry, but also validating new scientific contributions for the engineering of software functions. PRISE combines embedded and simulation platforms, and modeling tools. This platform is available for both research and teaching. Being built around widely used commercial and open source software; PRISE aims at being a reference platform for our teaching and research activities at ISAE

Running real time distributed simulations under Linux and CERTI

This paper presents some experiments and some results to enforce real time distributed simulations in accordance with the High Level Architecture (HLA). Simulations were run by using CERTI, an open source middleware, as the Run Time Infrastructure (RTI). Models were distributed over computers under various available versions of the 2.6 Linux kernel. Studies and experiments relied on a real case study. The chosen case study was the simulation of an "in formation" flight of observation satellites. This case study brings up some real applicative needs in real time distributed simulations and real configurations of simulators and models. Two simulations of "in formation" flight of satellites were studied. The study consisted in modeling the behaviour of the simulators and in running these models by using various kernel or middleware operating mechanisms and services. Time measurements were performed at each test giving some results on the ability of the simulation to meet its real time requirements

Towards an HLA Run-time Infrastructure with Hard Real-time Capabilities

Our work takes place in the context of the HLA standard and its application in real-time systems context. The HLA standard is inadequate for taking into consideration the different constraints involved in real-time computer systems. Many works have been invested in order to providing real-time capabilities to Run Time Infrastructures (RTI) to run real time simulation. Most of these initiatives focus on major issues including QoS guarantee, Worst Case Transit Time (WCTT) knowledge and scheduling services provided by the underlying operating systems. Even if our ultimate objective is to achieve real-time capabilities for distributed HLA federations executions, this paper describes a preliminary work focusing on achieving hard real-time properties for HLA federations running on a single computer under Linux operating systems. Our paper proposes a novel global bottom up approach for designing real-time Run time Infrastructures and a formal model for validation of uni processor to (then) distributed real-time simulation with CERTI

Ingénierie dirigée par les modèles pour la simulation, le cas de PRISE

Dans cet article, nous présentons une approche dirigée par les modèles permettant de fournir une vision haut niveau d’une simulation basée sur le standard HLA « High Level Architecture » sous forme d’un modèle AADL. Cette modélisation permet d’abstraire les paramètres clés d’une fédération HLA, de générer le code utile en lieu et place d’une écriture manuelle et de vérifier certains paramètres clés

HLA high performance and real-time simulation studies with CERTI

Our work takes place in the context of the HLA standard and its application in real-time systems context. Indeed, current HLA standard is inadequate for taking into consideration the different constraints involved in real-time computer systems. Many works have been invested in order to provide real-time capabilities to Run Time Infrastructures (RTI). This paper describes our approach focusing on achieving hard real-time properties for HLA federations through a complete state of the art on the related domain. Our paper also proposes a global bottom up approach from basic hardware and software basic requirements to experimental tests for validation of distributed real-time simulation with CERTI

Distributed Simulation of Heterogeneous and Real-time Systems

This work describes a framework for distributed simulation of cyber-physical systems (CPS). Modern CPS comprise large numbers of heterogeneous components, typically designed in very different tools and languages that are not or not easily composeable. Evaluating such large systems requires tools that integrate all components in a systematic, well-defined manner. This work leverages existing frameworks to facilitate the integration offers validation by simulation. A framework for distributed simulation is the IEEE High-Level Architecture (HLA) compliant tool CERTI, which provides the infrastructure for co-simulation of models in various simulation environments as well as hardware components. We use CERTI in combination with Ptolemy II, an environment for modeling and simulating heterogeneous systems. In particular, we focus on models of a CPS, including the physical dynamics of a plant, the software that controls the plant, and the network that enables the communication between controllers. We describe the Ptolemy extensions for the interaction with HLA and demonstrate the approach on a flight control system simulation

Real-Time Distributed Aircraft Simulation through HLA

This paper presents some ongoing researches carried out in the context of the PRISE (Research Platform for Embedded Systems Engineering) Project. This platform has been designed to evaluate and validate new embedded system concepts and techniques through a special hardware and software environment. Since many actual embedded equipments are not available, their corresponding behavior is simulated using the HLA architecture, an IEEE standard for distributed simulation, and a Run-time infrastructure called CERTI and developed at ONERA. HLA is currently largely used in many simulation applications, but the limited performances of the RTIs raises doubts over the feasibility of HLA federations with real-time requirements. This paper addresses the problem of achieving real-time performances with HLA. Several experiments are discussed using well-known aircraft simulators such as the Microsoft Flight Simulator, FlightGear, and X-plane connected with the CERTI Run-time Infrastructure. The added value of these activities is to demonstrate that according to a set of innovative solutions, HLA is well suited to achieve hard real time constraints